SG5841

The highly integrated SG5841/J series of PWM controllers provides several features to enhance the performance of flyback converters.

To minimize standby power consumption, a proprietary green-mode function provides off-time modulation to continuously decrease the switching frequency at light-load conditions. This green-mode function enables the power supply to meet international power conservation requirements. To further reduce power consumption, SG5841/J is manufactured using the BiCMOS process. This allows a low start-up current, around 14?A, and an operating current of only 4mA. As a result, a large start-up resistance can be used.

The SG5841/J built-in synchronized slope compensation achieves stable peak-current-mode control. The proprietary internal sawtooth power-limiter ensures constant output power limit over a wide range of AC input voltages, from 90V_AC to 264V_AC.

SG5841/J provides many protection functions. In addition to cycle-by-cycle current limiting, the internal open-loop protection circuit ensures safety should an open-loop or output-short-circuit failure occur. PWM output is disabled until V_DD drops below the UVLO lower limit, then the controller starts again. An external NTC thermistor can be applied for over-temperature protection.

SG5841/J is available in an 8-pin DIP or SOP package.